Laminar flow winglet

ABSTRACT

An aircraft wing tip device may include a unitized, monolithic leading edge torque box that may be formed of polymer matrix fiber-reinforced material. The leading edge torque box may include a skin that may define a continuous, uninterrupted outer mold line surface extending aftwardly from a winglet leading edge by a distance of at least approximately 60 percent of a local chord length. The leading edge torque box may further include at least one internal component extending between opposing inner surfaces of the skin and being integrally formed therewith.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a divisional application of and claimspriority to pending U.S. application Ser. No. 13/665,659 filed on Oct.31, 2012, and entitled NATURAL LAMINAR FLOW WINGTIP, the entire contentsof which is expressly incorporated by reference herein.

FIELD

The present disclosure relates generally to wing tip devices and, moreparticularly, to hollow wing tip devices formed of composite materialsin closed molds.

BACKGROUND

Winglets provide a means to reduce the negative effects of lift-inducedwing drag by effectively increasing the length of the trailing edge ofthe wing. The effective increase in the length of the trailing edge mayspread out the distribution of the vortices that are shed by thetrailing edge and the wing tip as the wing flies through the air. There-distribution of vortices may reduce aerodynamic losses fromlift-induced drag. Advantageously, winglets may provide an increase ineffective trailing edge length without increasing the length of the wingleading edge. In this regard, by adding winglets to the wings instead ofincreasing the wing span in the conventional manner, the added weight,cost, and complexity associated with the lengthening of leading edgelift-enhancement devices (e.g., slats, Krueger flaps) may be avoided.

Conventional winglets are fabricated as a hybrid assembly of componentsformed of different materials. For example, conventional winglets may becomprised of composite spars and skin panels that may be joined to ametallic leading edge and a metallic trailing edge, and which mayinclude metallic attach fittings. Unfortunately, the assembly of thewinglet components is a time-consuming and labor-intensive processrequiring a large quantity of mechanical fasteners. The large quantityof fasteners may increase the overall weight of the winglets. Inaddition, specialized tooling may be required for maintaining therelative positions of the components during fastener installation.

Furthermore, fasteners that are installed in the outer mold line (OML)surface of the winglets may disrupt the airflow passing over the OMLsurface. The disruption in airflow may minimize the distance over whichthe airflow is maintained in a laminar state before the airflow becomesturbulent with a resulting increase in aerodynamic drag. For example, inconventional winglets, the distance over which the airflow is laminarmay be limited to approximately 10% of the chord length, with thedownwind airflow becoming turbulent over the remaining portion of thewinglet. The increase in aerodynamic drag due to turbulent airflow overthe winglet may limit the gains in aircraft fuel efficiency that wouldbe possible if the airflow were maintained in a laminar state over alonger portion of the winglet chord length.

As can be seen, there exists a need in the art for a wingletconfiguration that maintains the air flow in a laminar state over arelatively large portion of the chord length prior to the airflowbecoming turbulent.

SUMMARY

The above-noted needs associated with wing tip devices such as wingletsare specifically addressed and alleviated by the present disclosurewhich provides an aircraft wing tip device including a unitized,monolithic leading edge torque box formed of polymer matrixfiber-reinforced material. The leading edge torque box may include askin that may define a continuous, uninterrupted outer mold line surfaceextending aftwardly from a winglet leading edge by a distance ofapproximately 60 percent or more of a local chord length. The leadingedge torque box may further include at least one internal componentextending between opposing inner surfaces of the skin and beingintegrally formed therewith.

In a further embodiment, disclosed is wing tip device having a unitized,monolithic leading edge torque box formed of polymer matrixfiber-reinforced material. The leading edge torque box may include askin that may define a continuous, uninterrupted, outer mold linesurface that may extend aftwardly from the winglet leading edge by adistance of at least 60 percent or more of a local chord length. Theleading edge torque box may further include an internal componentextending between opposing inner surfaces of the skin and beingintegrally formed therewith. The leading edge torque box may comprise aco-cured assembly of composite layups of the skin and the internalcomponent. The wing tip device may include a trailing edge section thatmay be joined to the torque box aft end.

Also disclosed is a method of maintaining laminar flow over a wing tipdevice. The method may include passing airflow over an OML surface of aunitized, monolithic, leading edge torque box of a wing tip device of anaircraft. The leading edge torque box may be formed of polymer matrixfiber-reinforced material and may include at least one internalcomponent extending between opposing inner surfaces of a skin. Themethod may further include maintaining the airflow in a laminar statepassing over the OML surface from a winglet leading edge aftwardly to adistance of at least 60 percent of a local chord length of the wing tipdevice.

The features, functions and advantages that have been discussed can beachieved independently in various embodiments of the present disclosureor may be combined in yet other embodiments, further details of whichcan be seen with reference to the following description and drawingsbelow.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features of the present disclosure will become moreapparent upon reference to the drawings wherein like numbers refer tolike parts throughout and wherein:

FIG. 1 is a perspective view of an aircraft having winglets;

FIG. 2 is a side view of a winglet having a unitized, monolithic,leading edge torque box formed of composite material;

FIG. 3 is a front view of the winglet shown in FIG. 2;

FIG. 4 is an exploded side view of a winglet including the leading edgetorque box and a separate trailing edge section that be attached to theleading edge torque box;

FIG. 5 is a sectional side view of an assembly of composite layups of askin and internal spars that may be co-cured into a unitized, monolithicleading edge torque box;

FIG. 6 is a sectional side view of a unitized, monolithic leading edgetorque box taken along line 6 of FIG. 2 and illustrating a trailing edgesection joined to an aft end of the leading edge torque box; and

FIG. 7 is a flow diagram illustrating one or more operations that may beincluded in a method of maintaining laminar flow over a wing tip device.

DETAILED DESCRIPTION

Referring now to the drawings wherein the showings are for purposes ofillustrating preferred and various embodiments of the disclosure, shownin FIG. 1 is a perspective view of an aircraft 100 having a fuselage 102extending from a nose of the aircraft 100 to an empennage of theaircraft 100. The empennage may include one or more tail surfaces fordirectional control of the aircraft 100. The aircraft 100 may furtherinclude a pair of wings 106 and a pair of propulsion units 104 that maybe mounted to the wings 106. The aircraft 100 may include one or moreaerodynamic structures 152 configured as wing tip devices 107 and whichmay be fabricated from composite material. In an embodiment, the wingtip devices 107 may comprise winglets 108 mounted on the tips of thewings 106.

Advantageously, the wing tip device 107 disclosed herein includes aunitized, monolithic, integrally-formed, composite leading edge torquebox 172 having a smooth, continuous, uninterrupted, outer mold line(OML) surface 122 that extends from the winglet leading edge 114 to anaft end 174 (FIG. 2) of the leading edge torque box 172. The continuous,uninterrupted OML surface 122 of the unitized leading edge torque box172 is configured such that airflow 146 over the OML surface 122 ismaintained in a laminar state 143 over a distance from the wingletleading edge 114 of at least approximately 60 percent of the local chord138 length (FIG. 6). In the present disclosure, the local chord isdefined as a line extending between the forward-most point on theleading to an aft-most point on the trailing edge of an airfoil sectiondefined by a plane oriented generally parallel to a forward direction ofthe aircraft. Although the wing tip device 107 and leading edge torquebox 172 disclosed herein are described in the context of a winglet 108,the wing tip device 107 may be provided in any size, shape, andconfiguration, without limitation. For example, the wing tip device 107may be configured as a raked wing tip (not shown), a split winglethaving upper and lower winglets (not shown), or in other wing tip deviceconfigurations.

Referring to FIG. 2, shown is a side view of an embodiment of a winglet108. The winglet 108 may include a winglet root 112 which may be joinedto a wing 106 of an aircraft 100. The winglet 108 may further include awinglet tip 110, a winglet leading edge 114, and a winglet trailing edge116. The leading edge torque box 172 may extend from winglet leadingedge 114 to the torque box aft end 174. The winglet trailing edge 116may be defined by a separately-attached trailing edge section 180. In anembodiment, the winglet trailing edge section 180 may be separatelyformed from the winglet 108 and may be attached to the torque box aftend 174 such as by mechanical fastening and/or adhesive bonding asdescribed below.

In FIG. 2, the unitized, composite leading edge torque box 172 may havea generally hollow configuration with three-dimensional geometry 126comprised of a composite skin 160 and one or more internal components158 formed of composite material. The internal components 158 maycomprise composite stiffeners 162 or composite spars 164 extendingbetween inner surfaces 120 of the composite skin 160 for increasing thebending stiffness and strength of the winglet 108. However, it iscontemplated that the trailing edge section 180 and the leading edgetorque box 172 may be integrally formed into a unitized, monolithic,composite structure such that the winglet 108 comprises a single,unitary structure from the winglet leading edge 114 to the winglettrailing edge 116. Although a unitary structure from the winglet leadingedge 114 to the winglet trailing edge 116 is not shown, such anarrangement may result in a winglet 108 having a substantiallycontinuous, uninterrupted, outer mold line (OML) surface 122 which mayresult in laminar airflow 143 along a substantial portion of thedistance from the winglet leading edge 114 to the winglet trailing edge116. For example, an uninterrupted, outer mold line (OML) surface 122from the winglet leading edge 114 to the winglet trailing edge 116 mayresult in laminar airflow 143 over a distance from the winglet leadingedge 114 of greater than approximately 80 percent of the local chord 138length (FIG. 6).

The unitized, monolithic, leading edge torque box 172 may be formedusing a tooling system (not shown) comprising an outer mold line (OML)tool and one or more inner mold line (IML) tools or mandrels positionedwithin the OML tool. The IML tools or mandrels may be formed of a rangeof materials including, but not limited to, rigid composite mandrelscovered by thin film or molded vacuum barrier materials, and/orexpandable mandrels that expand when exposed to heat causing theexpandable mandrels to generate internal compaction pressure forconsolidation of the polymer matrix fiber-reinforced material 157. TheIML tools or mandrels may also be formed of rigid, soluble mandrels orremovable rigid tools that have rates of thermal expansion matching thecomposite material of the composite article 150 being formed. Forexample, the IML tools may generate internal compaction pressure of theskin 160 against an OML tool surface (not shown) while simultaneouslygenerating internal compaction pressure against an internal component158 positioned between a pair of the IML tools. Advantageously, thetooling system may provide a means for co-consolidating and/or co-curingcomposite laminates that make up the skin 160 and the internalcomponents 158 to produce a hollow, unitized, three-dimensionalcomposite structure without the need for assembling winglet componentsby adhesive bonding or mechanical fastening. Three-dimensional geometry126 may be defined as internal components 158 that extend laterallyinwardly from the inner surfaces 120 of the skin 160 such as thecomposite spars 164 that extend between the opposing inner surfaces 120of the composite skin 160 on the upper side 132 and the lower side 134of the winglet 108 in FIG. 2.

Referring to FIG. 3, shown is a front view of the winglet 108illustrating the attachment to a wing tip of a wing 106. The winglet 108may include a curved transition 128 for transitioning the winglet 108from a generally horizontal orientation or slight dihedral of the wing106 to a canted section 129 of the winglet 108. The curved transition128 may represent non-draftable geometry 124 of the winglet 108 whereinthe winglet root 112 is curved at a juncture with the wing 106. Innon-draftable geometry 124, conventional internal tooling may beincapable of being extracted by sliding out of the interior of a curedcomposite article. However, the tooling system as may be used formanufacturing the leading edge torque box 172 disclosed herein mayinclude the use of soluble internal tooling (not shown) that may besolubilized or dissolved using water or other polar solvents into apartially liquid state to allow for removal of the internal tooling bypouring the solubilized internal tooling out of the end of the curedcomposite article.

In FIG. 3, the winglet 108 is shown with a canted section 129 that isrelatively straight along a spanwise direction 136 of the winglet 108.However, the canted section 129 may be curved and/or twisted along aspanwise direction 136 and/or the winglet 108 may have othernon-draftable geometry 124 such as a swept winglet tip cap (not shown).In the embodiment shown, the winglet 108 has a winglet root 112 with achord length that is substantially equivalent to a chord length of thewing tip. However, the winglet root 112 may be formed with a chordlength that is less than the chord length of the wing tip. The chordlength of the winglet 108 may taper at a relatively high rate within thecurved transition 128 after which the winglet 108 may taper at a reducedrate from the end of the curved transition 128 toward the winglet tip110. The winglet 108 may be oriented at an outward cant angle of betweenapproximately 0-45 degrees relative to vertical. However, the winglet108 may be oriented at any cant angle, without limitation.

Referring to FIG. 4, shown is a side view of the winglet 108 includingthe unitized, monolithic leading edge torque box 172 to which a separatetrailing edge section 180 may be attached. The trailing edge section 180may be formed of metallic material and/or composite material and may bejoined to the torque box aft end 174. For example, the trailing edgesection 180 may be attached to a rear spar 170 that may be included withthe leading edge torque box 172 and which may be located at the torquebox aft end 174. In an embodiment, the trailing edge section 180 mayinclude a forward end 184 that may be mechanically fastened oradhesively bonded to the torque box aft end 174 as described below.

In FIG. 4, the leading edge torque box 172 may include one or moreinternal components 158 such as one or more spars 164 extending at leastpartially along a spanwise direction 136 of the wing tip device 107. Forexample, the leading edge torque box 172 may include a front spar 166and a rear spar 170. The front spar 166 may be located aft of thewinglet leading edge 114. The rear spar 170 may be located at the torquebox aft end 174. The front spar 166 and the rear spar 170 may extendbetween and/or may interconnect the opposing inner surfaces 120 of theskin 160 on the upper side 132 and the lower side 134 of the winglet108. The leading edge torque box 172 may include a mid spar 168 locatedbetween the front spar 166 and the rear spar 170 for stiffness andstrength. One or more of the spars 164 may extend from the winglet root112 to the winglet tip 110. However, one or more of the spars 164 mayextend between any two locations between the winglet root 112 and thewinglet tip 110. In this regard, the spars 164 are not limited toextending between the winglet root 112 and winglet tip 110

Referring to FIG. 5, shown is a sectional side view of an assembly 154of composite layups 156 of the skin 160 and the front spar 166, mid spar168, and rear spar 170 and which may be co-cured with the skin 160 intothe unitized, monolithic leading edge torque box 172. In this regard,the leading edge torque box 172 may be formed as a co-consolidated andco-cured assembly 154 of composite layups 156 of the skin 160 and theinternal component 158 as mentioned above. In an embodiment, thecomposite layups 156 may comprise thermosetting composite material,thermoplastic composite material, pre-impregnated composite material,and/or resin-infused composite material polymer matrix. The polymermatrix fiber-reinforced material 157 may include carbon fibers, glassfibers, ceramic fibers, or other fibers types in a polymeric material orresin matrix such as epoxy. The resin matrix may comprise athermosetting resin, or the resin matrix may comprise a thermoplasticresin.

Referring to FIG. 6, shown is a sectional view of the unitized leadingedge torque box 172 with integrally processed (e.g., co-cured)three-dimensional geometry 126 including the composite internalcomponents 158 (e.g. spars 164) integrally-formed with the compositeskin 160. As indicated above, the leading edge torque box 172advantageously provides a unitized, integrally-formed, aerodynamicstructure having a smooth and dimensionally-precise OML surface 122. Theskin 160 defines a continuous, uninterrupted, outer mold line (OML)surface 122 on the upper side 132 and the lower side 134 of the winglet108. The spars 164 and/or other internal component 158 (e.g., stiffeners162, ribs—not shown) are shown oriented generally transverse to the skin160. The spars 164 may be positioned at any location between the wingletleading edge 114 and an aft end 174 of the leading edge torque box 172.The front spar 166 and skin 160 may define an integrally-formed leadingedge section 130 extending from the winglet leading edge 114 to thefront spar 166. The leading edge torque box 172 may provide torsionalrigidity and bending stiffness to the winglet 108 to resist deflectionunder static and/or dynamic loading that may undesirably alter theaerodynamics of the winglet 108.

In FIG. 6, the trailing edge section 180 may comprise at least twoseparate panels including a trailing edge upper panel 184 and a trailingedge lower panel 186. The trailing edge upper panel 184 and the trailingedge lower panel 186 may each have a forward end 184 that may be joinedto the torque box aft end 174. For example, the forward end 184 of eachone of the trailing edge upper panel 184 and a trailing edge lower panel186 may be mechanically fastened and/or an adhesively bonded to thetorque box aft end 174. In an embodiment, the torque box aft end 174 mayinclude a recess 176 extending in a spanwise direction 136 along thewinglet 108. The recess 176 may be sized and configured to receive theforward end 184 of the trailing edge upper panel 184 and trailing edgelower panel 186 such that the OML surface 122 of the upper side 132 andlower side 134 of the winglet 108 is at substantially the same level orheight as the trailing edge upper surface 188 and trailing edge lowersurface 190 respectively defined by the trailing edge upper panel 184and the trailing edge lower panel 186.

In addition, the torque box aft end 174 is preferably configured tominimize the width of a gap (not shown) that may occur between the aftedge of the OML surface 122 and the forward edge of the trailing edgeupper panel 184 and trailing edge lower panel 186. An aft end 182 of thetrailing edge upper panel 184 and the trailing edge lower panel 186 maybe joined together (e.g., mechanically fastened, adhesively bonded) at aconvergence thereof. However, the trailing edge section 180 may beformed as a unitary structure comprising the trailing edge upper panel184 and the trailing edge lower panel 186 integrally formed with thetrailing edge upper panel 184.

In FIG. 6, the leading edge torque box 172 may be configured such thatthe airflow 146 remains laminar over the OML surface 122 until theairflow 146 reaches a laminar-turbulent flow transition point 144 at anaft end of the OML surface 122 on the upper side 132 and the lower side134 of the wing. The location 140 of the laminar-turbulent flowtransition point 144 may be defined as a percentage of the local chordlength. For example, the leading edge torque box 172 may provide acontinuous, uninterrupted, OML surface 122 resulting in a laminar flowregion 142 that extends aftwardly from the winglet leading edge 114 by adistance of at least 60 percent of a local chord 138 length. However,the leading edge torque box 172 may be configured such that the airflow146 remains laminar over a distance from the winglet leading edge 114 ofat least 70 percent to 80 percent or more of the local chord 138 length.In the present disclosure, the OML surface 122 may comprise the surfaceof the winglet 108 that is exposed to the airflow 146 passing along theOML surface, and excludes surfaces of the leading edge torque box 172that are unexposed to the airflow 146.

Advantageously, the integrally-formed and unitized leading edge torquebox 172 provides an advantage over conventional winglet (not shown)construction which may include mechanical fasteners (not shown) in theOML surface in the area adjacent to the winglet leading edge. Forexample, conventional winglet construction may include a plurality ofmechanical fasteners installed at a junction of a separate leading edgeskin (not shown) and front spar (not shown). As indicated above, suchmechanical fasteners (not shown) in the OML surface may disrupt theairflow and may result in turbulent flow aft of the front spar (notshown) which may be located a distance from the winglet leading edge ofapproximately 10 percent or less of the local chord length. Disruptionof the airflow by such mechanical fasteners or by other discontinuitiesin the OML surface of conventional winglets may cause the airflow tobecome turbulent over a majority of the winglet which may increaseaerodynamic drag and reduce aerodynamic performance of the winglet.

Referring to FIG. 7, shown is a flow diagram illustrating one or moreoperations that may be included in a method 300 of maintaining laminarflow 143 (FIG. 6) over a wing tip device 107 such as the winglet 108illustrated and FIGS. 1-6.

Step 302 of the method 300 of FIG. 7 may include passing airflow 146(FIG. 6) over an outer mold line (OML) surface 122 of a unitized,monolithic leading edge torque box 172 of a wing tip device 107 of anaircraft 100. FIG. 6 illustrates the oncoming airflow 146 passing overthe winglet leading edge 114. As indicated above, the leading edgetorque box 172 is formed a unitized, integrally-formed, compositestructure having a smooth, uninterrupted, and continuous OML surface122. In addition, the leading edge torque box 172 provides adimensionally-precise contour and finish of the OML surface 122 which isimparted by use of an OML tool (not shown) in combination of one or moreinner mold line (IML) tools (not shown) to generate internal compactionpressure (not shown) of the skin 160 against a precisely-controlledcontour and finish of the OML tool surface (not shown).

Step 304 the method 300 of FIG. 7 may include maintaining the airflow146 in a laminar state 143 when passing the airflow 146 over the OMLsurface 122 of the winglet 108 from the winglet leading edge 114aftwardly to a distance of at least 60 percent more of a local chord 138length of the winglet 108. In an embodiment, the leading edge torque box172 airflow 146 may be configured such that the torque box aft end 174is located at a distance from the leading edge of 60-70 percent or moreof the local chord 138 length such that the airflow 146 remains laminarat least until reaching the torque box aft end 174. The method mayinclude maintaining the airflow 146 in a laminar state 143 while passingthe airflow 146 over the winglet 108 from the curved transition 128located between the wing tip and the canted section 129 of the winglet108.

Step 306 the method 300 of FIG. 7 may include passing the airflow 146over a trailing edge section 180 that may be joined to the torque boxaft end 174 such as by mechanically fastening and/or adhesively bonding.The torque box aft end 174 may represent a laminar-turbulent flowtransition point 144 where the airflow 146 may transition from laminarflow 143 (FIG. 6) to turbulent flow downwind of the laminar-turbulentflow transition point 144. The turbulent flow may result from disruptionof the airflow 146 at the juncture between the trailing edge section 180and the aft edge of the OML surface 122 of the leading edge torque box172. For example, turbulent flow may result from airflow disruption dueto mechanical fasteners installed in the OML surface and/or as a resultin a gap or a difference in height between the forward end 184 of thetrailing edge section 180 and the aft end of the OML surface 122 of thetrailing edge torque box.

Advantageously, the wing tip device 107 disclosed herein provides ameans for achieving natural laminar flow over a wing tip device 107 suchas a winglet 108 without the use of flow enhancement devices such as aporous skin surface (not shown) or other devices. In addition, theunitary, monolithic, leading edge torque box 172 advantageously providesa continuous, uninterrupted OML surface 122 from the winglet leadingedge 114 to an aft end of the leading edge torque box 172. By providinga tightly-controlled contour and finish on the OML surface 122 of theleading edge torque box 172, disruption of the airflow 146 may beminimized such that the airflow 146 may be maintained in a laminar state143.

Additional modifications and improvements of the present disclosure maybe apparent to those of ordinary skill in the art. Thus, the particularcombination of parts described and illustrated herein is intended torepresent only certain embodiments of the present disclosure and is notintended to serve as limitations of alternative embodiments or deviceswithin the spirit and scope of the disclosure.

What is claimed is:
 1. A wing tip device for an aircraft, comprising: aunitized, monolithic leading edge torque box formed of polymer matrixfiber-reinforced material and including: a skin defining a continuous,uninterrupted outer mold line (OML) surface extending aftwardly from awinglet leading edge by a distance of at least approximately 60 percentof a local chord length; and at least one internal component extendingbetween opposing inner surfaces of the skin and being integrally formedtherewith.
 2. The wing tip device of claim 1, wherein: the leading edgetorque box is formed as a co-cured assembly of composite layups of theskin and the internal component.
 3. The wing tip device of claim 2,wherein: the composite layups comprise at least one of thermosettingcomposite material, thermoplastic composite material, pre-impregnatedcomposite material, and resin-infused composite material.
 4. The wingtip device of claim 1, wherein: the internal component comprises a sparextending at least partially along a spanwise direction of the wing tipdevice.
 5. The wing tip device of claim 4, wherein: the leading edgetorque box includes a front spar and a rear spar; the front spar beinglocated aft of the winglet leading edge; and the rear spar being locatedat a torque box aft end.
 6. The wing tip device of claim 1, wherein: thewing tip device comprises one of a raked wing tip and a split winglethaving upper and lower winglets.
 7. The wing tip device of claim 1,wherein: the wing tip device comprises a winglet configured to extendoutwardly from a wing of the aircraft.
 8. The wing tip device of claim1, wherein: the winglet includes a curved transition for transitioningthe winglet from a wing tip of the wing to a canted section of thewinglet.
 9. The wing tip device of claim 1, further comprising: atrailing edge section joined to a torque box aft end.
 10. The wing tipdevice of claim 9, wherein: the trailing edge section is attached to arear spar located at the torque box aft end.
 11. The wing tip device ofclaim 9, wherein: a forward end of the trailing edge section ismechanically fastened to the torque box aft end.
 12. The wing tip deviceof claim 9, wherein: the trailing edge section comprises at least twoseparate panels including a trailing edge upper panel and a trailingedge lower panel; and the trailing edge upper panel and the trailingedge lower panel each having a forward end being joined to the torquebox aft end.
 13. The wing tip device of claim 9, wherein: the trailingedge section comprises a unitary structure including a trailing edgeupper panel and a trailing edge lower panel integrally formed with thetrailing edge upper panel.
 14. A winglet for an aircraft, comprising: aunitized, monolithic leading edge torque box formed of polymer matrixfiber-reinforced material and including: a skin defining a continuous,uninterrupted outer mold line (OML) surface extending aftwardly from awinglet leading edge by a distance of at least approximately 60 percentof a local chord length; and at least one spar oriented along a spanwisedirection of the winglet and extending between opposing inner surfacesof the skin and being integrally formed therewith.
 15. The winglet ofclaim 14, wherein: the leading edge torque box is formed as a co-curedassembly of composite layups of the skin and the at least one spar. 16.The winglet of claim 14, wherein: the winglet includes a curvedtransition for transitioning the winglet from a wing tip of an aircraftwing to a canted section of the winglet when mounted to the wing tip.17. The winglet of claim 14, further including: a trailing edge sectionintegrally formed with the leading edge torque box into a unitized,monolithic, composite structure such that the winglet comprises asingle, unitary structure from the winglet leading edge to the winglettrailing edge.
 18. An aircraft, comprising: a wing having a wing tip; awinglet formed as a unitized, monolithic leading edge torque box formedof polymer matrix fiber-reinforced material, including: a skin defininga continuous, uninterrupted outer mold line (OML) surface extendingaftwardly from a winglet leading edge by a distance of at leastapproximately 60 percent of a local chord length; and at least one sparoriented along a spanwise direction of the winglet and extending betweenand integrally formed with opposing inner surfaces of the ski; and thewinglet extending outwardly from the wing tip.
 19. The aircraft of claim18, wherein: the winglet being oriented at an outward cant anglerelative to vertical.
 20. The aircraft of claim 19, wherein: the outwardcant angle is between approximately 0-45 degrees relative to vertical.